Compared to the species from the Neotropics, very little is known about many species from Indomalaya. Only a few attempts have been made for the phylogeny-based reclassification of the family, and those have been hampered by the Neotropic bias in the available information, with the most of the work having been done on genera and tribes.[5]

Flower stalks are axillary to (on the opposite side of shoot from) leaf scars on old wood and sometimes from leaves on new shoots. The flowers are usually trimerous; borne singly or in compound inflorescences; bisexual and rarely unisexual. The receptacle might become enlarged, elevated or flat. The outer whorls are inserted below the ovaries, and have valvate (overlapping) or imbricate (nonoverlapping) segments. Usually two to four persistent sepals that are distinct or connate (fused) at the base. Six petals in two unequal whorls of three with larger outer whorls and fleshier inner whorls that might share the same nectar glands, or six to fifteen petals, with impressed veins on their inner face. Ten to twenty (or many more) stamens inserted below the ovary, spirally arranged and forming a ball or flat-topped mass with short and stout filaments and linear to oblong anthers which face outward and open longitudinally. Each flower can have from one to many pistils, distinct to connate, with stigmas distinct. Marginal placentation, each pistil bearing one locule, with one to many ovules. Style short and thick, with terminal stigma.[3]

Fruits and seeds

Fruits are single berries or coalesce from several pistils (into aggregate fruit, syncarps). Seeds are one to many per pistil; have a fleshy and usually brightly colored cover, have ruminate endosperm (nutritive tissue surrounding the embryo) and are oily.[3]

Combined plastid DNA marker and morphological character analysis of Anaxagorea and other Annonaceae and basal angiosperm genera suggest that Anaxagorea is an ancestral clade, sister to the rest of the family. This may confirm the hypothesis that morphological traits shared with other Magnoliales species (such as 2-ranked phyllotaxis, monosulcate pollen, and laminate stamens) represent ancestral characters, while derived characters observed in other genera have evolved independently multiple times. These analyses also support a biogeographic history in which Annonaceae, and perhaps other basal angiosperm clades, originated in South America during the Cretaceous, radiating due to migration events throughout Africa to Asia and Central to North America.[8][9]

Guatteria, with its approximately 265 species, is the largest genus of Annonaceae, and might be broken into three small genera based on molecular characters from multiple locations.[10]

Tribe Saccopetaleae is another group of Annonaceae that is awaiting review as recent molecular studies suggest that this tribe is not monophyletic at all.[11]

The large, edible, pulpy fruits of some members typically called "anona" by Spanish and Portuguese speaking people of the family's Neotropical range, include species of Annona: custard apple (A. reticulata), cherimoya (A. cherimola), soursop/guanábana/graviola (A. muricata), sweetsop (A. squamosa), ilama (A. diversifolia), soncoya (A. purpurea), atemoya (a cross between A. cherimola and A. squamosa); and biriba (Rollinia deliciosa, which may require reclassification under Annona.[1]). The names of many of those fruits are sometimes used interchangeably. Recently, consumption of the neotropical annonaceous plant Annona muricata (soursop, graviola, guanabana) has been strongly associated as a causal agent in "atypical Parkinsonsism". The causative agent, annonacin, is present in many of the annonaceae. It is thought to be responsible for up to 70% of Parkinsonian conditions in Guadeloupe. Exposure is typically through traditional food and natural medicines.[12][13][14][15]

It is brought into commerce in the form of taper poles of about 6 metres in length and from 15 to 20 cm in breadth at the butt. The black lancewood or carisiri of The Guianas is of remarkably slender form.

The Yellow lancewood tree Calycophyllum candididissimum, common names lemonwood or degame, is from a different family (Rubiaceae).[17] It is used as an alternative to lancewood and is found in tolerable abundance throughout The Guianas, and used by the Amerinds for arrow-points, as well as for spars, beams, etc. Some bowyers use this wood for making longbows.

A large number of chemical compounds, including flavonoids, alkaloids, and acetogenins, have been extracted from the seeds and many other parts of these plants. Flavonoids and alkaloids contained in the leaves and bark of several species of the family have shown insecticidal properties.[18]

The compound annonacin contained in the seeds of some members of Annonaceae such as Annona muricata (soursop) is a neurotoxin and it seems to be the cause of a neurodegenerative disease. The disorder is a so-called tauopathy associated with a pathologic accumulation of tau protein in the brain. Experimental results demonstrate that the plant neurotoxin annonacin is responsible for this accumulation.[20]